/*
* Copyright 2002-2008 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.jdbc.support;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.jdbc.CannotGetJdbcConnectionException;
/**
* Bean that checks if a database has already started up. To be referenced
* via "depends-on" from beans that depend on database startup, like a Hibernate
* SessionFactory or custom data access objects that access a DataSource directly.
*
* <p>Useful to defer application initialization until a database has started up.
* Particularly appropriate for waiting on a slowly starting Oracle database.
*
* @author Juergen Hoeller
* @since 18.12.2003
*/
public class DatabaseStartupValidator implements InitializingBean {
public static final int DEFAULT_INTERVAL = 1;
public static final int DEFAULT_TIMEOUT = 60;
protected final Log logger = LogFactory.getLog(getClass());
private DataSource dataSource;
private String validationQuery;
private int interval = DEFAULT_INTERVAL;
private int timeout = DEFAULT_TIMEOUT;
/**
* Set the DataSource to validate.
*/
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
/**
* Set the SQL query string to use for validation.
*/
public void setValidationQuery(String validationQuery) {
this.validationQuery = validationQuery;
}
/**
* Set the interval between validation runs (in seconds).
* Default is 1.
*/
public void setInterval(int interval) {
this.interval = interval;
}
/**
* Set the timeout (in seconds) after which a fatal exception
* will be thrown. Default is 60.
*/
public void setTimeout(int timeout) {
this.timeout = timeout;
}
/**
* Check whether the validation query can be executed on a Connection
* from the specified DataSource, with the specified interval between
* checks, until the specified timeout.
*/
public void afterPropertiesSet() {
if (this.dataSource == null) {
throw new IllegalArgumentException("dataSource is required");
}
if (this.validationQuery == null) {
throw new IllegalArgumentException("validationQuery is required");
}
try {
boolean validated = false;
long beginTime = System.currentTimeMillis();
long deadLine = beginTime + this.timeout * 1000;
SQLException latestEx = null;
while (!validated && System.currentTimeMillis() < deadLine) {
Connection con = null;
Statement stmt = null;
try {
con = this.dataSource.getConnection();
stmt = con.createStatement();
stmt.execute(this.validationQuery);
validated = true;
}
catch (SQLException ex) {
latestEx = ex;
logger.debug("Validation query [" + this.validationQuery + "] threw exception", ex);
float rest = ((float) (deadLine - System.currentTimeMillis())) / 1000;
if (rest > this.interval) {
logger.warn("Database has not started up yet - retrying in " + this.interval +
" seconds (timeout in " + rest + " seconds)");
}
}
finally {
JdbcUtils.closeStatement(stmt);
JdbcUtils.closeConnection(con);
}
if (!validated) {
Thread.sleep(this.interval * 1000);
}
}
if (!validated) {
throw new CannotGetJdbcConnectionException(
"Database has not started up within " + this.timeout + " seconds", latestEx);
}
float duration = (System.currentTimeMillis() - beginTime) / 1000;
if (logger.isInfoEnabled()) {
logger.info("Database startup detected after " + duration + " seconds");
}
}
catch (InterruptedException ex) {
// Re-interrupt current thread, to allow other threads to react.
Thread.currentThread().interrupt();
}
}
}
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